Getting free moves without paying for them seems inconsistent with all the other features of this game system. Seems like there should be some IPC expenditures in order to get movement bonuses and there should be a strict cap on the amount of units that can benefit from these investments in the territories’ transportation infrastructure.
Maybe something like this: “No more than 2 Infantry and/or Artillery units get one extra move by paying 1 IPC each during the Purchase New Units phase.”
I will discuss this with my gaming group, but it is unlikely that we will be using any house rules until we get more games of A&AEurope 1940 2nd edition under our belts.